ELEMENT FOR USE IN MAKING A REINFORCED CONCRETE STRUCTURE WITH CAVITIES, FILLER BODY FOR MAKING SUCH AN ELEMENT, AND METHOD OF MAKING A REINFORCED CONCRETE STRUCTURE WITH CAVITIES

Abstract: In an element for use in making a reinforced concrete structure of substantially planar shape and of the kind comprising: a) at least a lower reinforcing mesh consisting of mutually crossing reinforcing rods (1, 2) rigidly secured to each other, and b) a number of spaced filler bodies (3) of substantially identical shape and size cooperating with said lower mesh (1, 2) so as to locate them in a regular pattern corresponding to the pattern of said lower mesh (1, 2); the main novel feature is that said filler bodies (3) interengage (14) with said lower mesh (1, 2) so as to form a rigid body. With this arrangement, most of the work requiring precision and the use of specialized equipment can be done in a factory or workshop, while maintaining the advantages of using spaced filler bodies cooperating with the reinforcing mesh to provide cavities in the finished structure. The filler bodies (3) are preferably hollow for reasons of weight and economy, and comprise flanges (8) cooperating with each other to form a lower shuttering. Preferably also, an upper reinforcing mesh (1a, 2a) is used, further increasing the rigidity of the element.

Description: ELEMENT FOR USE IN MAKING A REINFORCED CONCRETE STRUCTURE WITH CAVITIES, FILLER BODY FOR MAKING SUCH AN ELEMENT, AND METHOD OF MAKING A REINFORCED CONCRETE STRUCTURE WITH CAVI- TIES. TECHNICAL FIELD The present invention relates to an element for use in making a reinforced concrete structure of the kind set forth in the preamble of claim 1. BACKGROUND ART The International PCT-application No. WO 92/06253 discloses a reinforced concrete structure capable of being made by using of an element of the kind referred to above. In this known structure, the filler bodies used for forming cavities in the structure are in the form of closed hollow spheres, ovoids or similar bodies, placed loosely in the squares formed by the mutually crossing reinforcing rods, when the latter have been placed in position ready for casting the desired concrete structure. This means, of course, that a considerable amount of work has to be done on the building site in placing and securing the filler bodies correctly in position in the squares of the mesh, and the "element" con¬ sisting of the reinforcing mesh and the filler bodies does in fact only exist for a short while prior to the casting step. A previously known method of saving weight in concrete deck structures comprises the following steps: placing in situ a pattern of filler bodies in the form of recess-forming boxes or cupolas, typically 1,2 m square, on a conventional deck shuttering, placing the reinforcements in situ, and finally casting or grouting. In this manner, a relatively light deck structure having mutually crossing reinforced ribs on the lower side can be produced. A disadvantage of this matter is, however, that substantially all the work has to be done on the building site, thus pre¬ cluding the use of industrial facilities with their attendant advantages with regard to rational and economical production. Another method comprises the use of the factory-made so-called "FILIGRAN" elements for providing both the rein¬ forcements and the shuttering, assembled in situ prior to the casting or grouting, likewise in situ. The disadvantage of this method consists in that the resulting structure is a compact deck without weight-reducing recesses, thus neces¬ sitating the use of more concrete than strictly necessary to achieve the desired strength. DISCLOSURE OF THE INVENTION It is the object of the present invention to provide an element of the kind referred to above, which does not suffer from the disadvantages described above, and this object is achieved with such an element, according to the present invention additionally exhibiting the feature set forth in the characterizing clause of claim 1. With this arrangement, the complete element comprising at least a lower reinforcing mesh and a number of filler bodies rigidly engaged therein may be manufactured in a factory or workshop having considerably better facilities for rational and accurate mass or series production than can possibly be available on a building site. Further, the complete element may be stored, handled and transported without need for taking special precautions, as the interengagement between the reinforcing mesh and the filler bodies makes the element self-supporting and quite rigid, and - not least - ready for immediate use upon arrival at the building site. Further still, the weight of the element is considerably less than that of pre-fabricated reinforced concrete elements, and in contradistinction to the latter, the elements according to the invention may be adapted to various structures in the building being erected. Apart from such adaptation, if any, the only work to be done on the building site is placing each element in position suitably supported, connecting it to the reinforcing mesh of any ad acent elements, placing pipes, cables and/or light fittings etc., and placing any shuttering around the element, before, preferably by means of a concrete pump, pouring in the concrete, being in fact the heaviest component of the finished structure, in this case not having to be transported from the factory, in which the elements are made. Compared to the above-mentioned previously known method of building deck structures with mutually crossing ribs, the use of elements according to the present invention makes it possible to do all the work of assembling the reinforcements and the weight-saving filler bodies in a factory, thus saving time and costs on in-situ work. Compared to the use of the "FILIGRAN" elements, the use of elements according to the present invention makes it possible to achieve a saving in weight of 30-55 %, thus also making greater spans possible. As mentioned under the previous heading, the filler bodies used in the Prior Art for forming cavities in the structure are in the form of closed hollow spheres, ovoids or similar bodies. With filler bodies of such shapes, concrete will unavoidably penetrate between the filler bodies and the lower side of the structure, in the case described a floor. For this reason, the lower face of the final concrete struc¬ ture will consist of a continuous layer of concrete serving no useful purpose, because it is unable to carry tensional stresses, these being taken up entirely by the reinforcing mesh. A further problem consists in that during grouting or casting, unhardened concrete will tend to make the filler bodies "float" upwardly, for which reason it is necessary to anchor them firmly. These disadvantages are avoided with the embodiment set forth in claim 2, preferably also inclu¬ ding the feature set forth in claim 3. With such an arrange¬ ment, no concrete will penetrate below the filler bodies, so that the lower side of the final concrete structure will comprise no more concrete than that immediately surrounding the rods in the reinforcing mesh, and the ensuing shape of the filler bodies also prevents unhardened concrete from penetrating below the filler bodies and making them "float", at the same time reducing considerably or even eliminating the need for lower shuttering. In addition, the rigid in- ter-engagement between the filler bodies and the reinforcing mesh will ensure that the latter is placed in the correct height above the structural parts constituting a temporary support for the element. The present invention also relates to a filler body for use in making a structural element according to the inven¬ tion, and this filler body is constructed as set forth in the characterizing clause of claim 13. Advantageous embodiments of the element and the filler body for use in making it are set forth in claims 4-12 and 13-18 respectively. BRIEF DESCRIPTION OF THE DRAWINGS In the following detailed portion of the present description, the invention will be explained in more detail with reference to the drawings, in which Fig. 1 is a perspective view of a part of a combined rein¬ forcement and shuttering element according to the invention, Fig. 2 is a top view of an element, in which filler bodies have been removed from some of the squares, placed in readi¬ ness for grouting or casting, Fig. 3 is a vertical section along the line III-III in Fig. 2 and showing the finished cast concrete structure after the shuttering has been removed, Figs. 4 and 5 are views corresponding to Figs. 2 and 3 res¬ pectively showing a slightly modified exemplary embodiment, Fig. 6 at an enlarged scale shows some details of the filler bodies used in the exemplary embodiment of Figs. 4 and 5, and Fig. 7 is a sectional view resembling Fig. 6, but shows an exemplary embodiment having twice as many upper reinforcing rods. DESCRIPTION OF THE PREFERRED EMBODIMENTS The part of a combined reinforcement and shuttering element shown in perspective in Fig. 1 is a rigid body consisting of - a number of crosswise lower reinforcing rods 1, - a number of lengthwise lower reinforcing rods 2, - a number of crosswise upper reinforcing rods la, - a number of lengthwise upper reinforcing rods 2a, and - a number of hollow filler bodies 3 secured below within the squares formed by the lower reinforcing mesh consti¬ tuted by the rods 1 and 2, and secured at the top to the upper mesh constituted by the rods la and 2a, said securing being achieved by means to be described below. When assembling an element, part of which is shown in Figure 1, the lower reinforcing mesh consisting of all the crosswise lower reinforcing rods 1 and the lengthwise lower reinforcing rods 2, preferably welded together so as to form a rigid structure, is placed in position on a suitable base. Then, the hollow bodies 3 are placed in the "squares" formed by the mesh, engaging the latter by means of locking ribs 14, the flanges 8 abutting sealingly against adjacent flanges, if any. The notches in the locking ribs 14 on the hollow bodies 3 for engagement with the crosswise lower reinforcing rods 1 are placed at a slightly higher level than those for the lengthwise lower reinforcing rods 2, so as to allow for the slight difference in level between the reinforcing rods caused by their finite thickness. These notches will ensure that the reinforcing mesh is placed at the correct level relative to the flanges 8, with which the finished element will rest on a suitable in-situ support prior to grouting or casting. The hollow bodies 3, vide also Fig. 3, are shaped roughly like inverted buckets, in the exemplary embodiment shown in Figs. 1-3 having a side-wall section 6 of roughly frusto-pyramidal shape, continuing upwardly in a domed top section 7 and downwardly into the above-mentioned flange 8, vide also Fig. 6. In the final assembling step, an upper reinforcing mesh consisting of the crosswise upper reinfor- cing rods la and the lengthwise upper reinforcing rods 2a is placed on top of the domed top sections 7, being held by resilient clamping fingers 16 formed integrally with the top sections 7 and projecting upwardly from the latter. An element formed in this manner is quite rigid, and will withstand stresses normally encountered in handling and transport. Further, due to the use of a lower reinforcing mesh 1,2 and an upper reinforcing mesh la,2a, rigidly inter¬ connected through the hollow bodies 3, the element will be able to withstand considerable loads, such as by being filled with concrete whilst resting on supports at a substantial distance from each other. The finished assembly consisting of the reinforcing meshes 1,2 and la,2a and the hollow bodies 3 - and even pipes, cables etc. forming parts of the final structure, and parts of any requisite shuttering secured thereto - may be trans¬ ported from the factory or workshop to the building site and placed in position, after which the process of grou¬ ting, setting of the concrete and removal of the shuttering will proceed in the usual manner. When grouting has taken place on the assembly shown in Fig. 2, and the concrete has set, a structure as shown in vertical section in Fig. 3 will have been produced. This structure comprises - of course - the parts shown in Figs. 1 and 2, as well as a monolithic concrete body 9 having an upper side 10 and a lower side 11. In the exemplary embodiment shown, the upper side 10 consists solely of a continuous body of concrete, reinforced by the upper reinforcing rods la and 2a, while the lower side 11 consists of a number of mutually crossing ribs bounding the downwardly facing open sides 12 of the hollow bodies 3, reinforced by the lower reinforcing rods 1 and 2. As will be seen in Fig. 2, the hollow bodies 3 have been removed from the squares surrounding a square, through which a column 4 extends. The shuttering 5 thus made necessary can be seen through these "empty" squares. The assembly of elements and the structure shown in Figs. 4 and 5 respectively correspond in principle to those shown in Figs. 1-3, differing solely in - that there is no column like the column 4 in Fig. 2, but instead a supporting wall 13, and - that the side-wall section 6 in each of the hollow bodies 3 is frusto-conical instead of frusto-pyramidal as in Figs. 1-3. Obviously, the same functions apply as described above with reference to Figs. 1-3. Fig. 6 shows more clearly - due to the enlarged scale - the construction of the hollow bodies 3 with regard to the flange 8 surrounding the open side 12 and the locking ribs 14 re¬ ferred to above. Thus, in the exemplary embodiment shown, the engagement means consist of a number of fin-like locking ribs 14 protruding from the outside of the side-wall section 6. Each locking rib 14 has a notch 15 adapted to cooperate with reinforcing rods 1 or 2, in the example shown in Fig. 6 one of the lengthwise reinforcing rods 2. As the crosswise reinforcing rods 1 will necessarily be at a level differing from the level of the lengthwise reinforcing rods 2, the notches 15 in the locking ribs 14 on the sides of the hollow bodies 3 adapted to cooperate with the crosswise reinfor¬ cing rods 1 will be placed at a different level than the level of the notch 15 shown in Fig. 6 cooperating with the lengthwise reinforcing rod 2. In order to achieve a stable interlocking of the hollow bodies 3 with the reinforcing mesh consisting of the reinforcing rods 1 and 2, at least two locking ribs 14 may be used on each side of each hollow body 3, i.e. a total of eight ribs on each hollow body. Other solutions are, however, possible. In the exemplary embodiment shown in Fig. 7, the upper re¬ inforcing mesh consists of crosswise upper reinforcing rods lb and lengthwise upper reinforcing rods 2b with a mutual spacing one-half of the mutual spacing between the crosswise lower reinforcing rods 1 and the lengthwise lower reinforcing rods 2. The upper reinforcing mesh is secured to the hollow bodies 3 by means of integrally formed locking ears 17 in the transition region between the side-wall section 6 and the top section 7, preferably in snap-fit fashion. This arrangement gives an increased rigidity of an element like the one illustrated in Fig. 1, in addition producing a more homogeneous reinforcing effect with regard to point-wise loading of the upper surface of the finished concrete struc- ture. If the hollow bodies 3 are produced, as is in fact preferred, by injection moulding suitable plastic material, such as PVC or polyethylene, both the locking ribs 14 on the outside of the side-wall section 6 and the clamping fingers 16 or the locking ears 17 on the top section 7 may be moulded integrally with the rest of the hollow bodies. As indicated above, the flanges 8 may be so shaped and dimen- sioned, that they are in mutual abutment or engagement, acting as local shuttering for the lower faces of the ribs containing the rods 1 and 2. If the hollow bodies are to remain as "permanent shuttering", this arrangement will also give the downwardly facing side of the structure, pos- sibly constituting a ceiling for the space below, a more pleasing appearance, at the same time protecting the concrete structure against aggressive media. Instead of being manufactured singly, the hollow bodies 3 may be manufactured in the form of webs with a width and length corresponding to the total width and length of an integral number of hollow bodies. In this case, the flanges 8 will be common to two adjoining bodies, and will - of course - be perfectly leak-proof with respect to the unhar- dened concrete. Such webs may be manufactured by any conven¬ tional method, such as by vacuum-forming plastic sheet ma- terial . In the exemplary embodiments described above and shown in the drawings, the filler bodies 3 are described and shown as being hollow. It is, however, possible to use compact filler bodies, preferably made from foamed plastic material, or hollow bodies substantially as described and shown, but having a filling of foamed plastic material. In the exemplary embodiments described above and shown in the drawings, all the reinforcing rods have been described and shown as each constituted by a single rod. It does, however, lie within the scope of the invention to use two, three, four or more parallel rods with mutual spacing, in place of these single rods. This especially applies to the lower reinforcing rods 1 and 2, providing tensional strength in the ribs forming the lower part of the finished structure, in which e.g. two rods may be placed on top of each other. The present invention was occasioned by the need to combine the advantages of mass or series production related to pre¬ fabricated concrete elements, with the adaptability and possibility of crosswise reinforcing achieved with in-situ casting, while at the same time reducing the transport costs relating to the heavy part of the building material, i.e. the concrete itself. As will be evident from the above description, the use of elements according to the invention, comprising the simul- taneous provision of shuttering, reinforcement and weight-reducing recesses, will be most useful with in-situ casting of concrete decks where there is a need of reducing the weight. Thus, the invention teaches a technology, that is simple with regard to the manufacturing aspect, for reducing the weight of the conventional crosswise-reinforced concrete slabs, by integrating recess-forming boxes or cupolas in the lower side of the concrete deck. When prefabricating elements according to the invention in a factory, the size of the elements will generally be de¬ termined by the available transport facilities, e.g. with a width of approx. 2,5 m and a length of 10-14 m. Thus, the size of the element is not closely related to the in-situ support or span conditions, as the finished deck will func¬ tion as a continuous load-supporting deck. The only work remaining to be done on the building site is essentially the placing of the elements in position, and then the grouting or casting, preferably by using a concrete pump. LIST OF PARTS 1 Crosswise lower reinforcing rods la Crosswise upper reinforcing rods 5 lb Crosswise upper reinforcing rods 2 Lengthwise lower reinforcing rods 2a Lengthwise upper reinforcing rods 2b Lengthwise upper reinforcing rods 3 Filler bodies 10 4 Column 5 Shuttering 6 Side-wall section 7 Top section 8 Flange 15 9 Monolithic concrete body 10 Upper side (of 9) 11 Lower side (of 9) 12 Open side (of 3) 13 Wall 20 14 Locking rib 15 Notch 16 Clamping fingers 17 Locking ears

Claims: CLAIMS . 1. Reinforcing element for use in making a reinforced concrete structure of substantially planar shape and of the kind comprising a) at least a lower reinforcing mesh consisting of mu¬ tually crossing reinforcing rods (1,2) rigidly secured to each other, and b) a number of spaced filler bodies (3) of substantially identical shape and size cooperating with said lower mesh (1,2) so as to locate them in a regular pattern corresponding to the pattern of said lower mesh (1,2), and characterized in c) that said filler bodies (3) interengage (14) with said lower mesh (1,2) so as to form a rigid body. 2. Element according to claim 1, characterized in that each of said filler bodies (3) has a major side (12) facing in the same direction as the lower side (11) of said structure. 3. Element according to claim 2, characterized in that each said filler body (3) comprises a flange (8) exten- ding outwardly from the edge of said body around said major side (12), said flange (8) being adapted to cooperate with similar flanges (8) in neighbouring elements so as to form a lower shuttering. 4. Element according to any one or any of the claims 1-3, characterized in that each said filler body (3) com¬ prises first engagement means (14,15) adapted to hold said filler body in engagement with said lower reinforcing mesh (1,2). 5. Element according to any one or any of the claims 1-4, characterized in that it comprises an upper reinforcing mesh (la,lb,2a,2b) held by second engagement means (16,17) in rigid engagement with the tops (7) of said filler bodies (3). 6. Element according to any one or any of claims 1-5, characterized in that each of said filler bodies (3) comprises a) a side-wall section (6) extending upwardly convergent- ly from the periphery of said open side (12) to b) a top section (7) contiguous with said side-wall section (6) and closing the opposite side of the hollow body (3). 7. Element according to claim 6, characterized in that said top section (7) is dome-shaped with a smooth transition from said side-wall section (6). 8. Element according to claim 6 or claim 7, charac- terized in that said side-wall section (6) is substantially square or rectangular as seen in cross-section in a plane parallel to the overall plane of the element. 9. Element according to claim 6 or claim 7, charac- terized in that said side-wall section (6) is substantially circular or elliptical as seen in cross-section in a plane parallel to the overall plane of the element. 10. Element according to any one or any of the claims 1-9, characterized in that at least one of said filler bodies (3) is hollow, said major side (12) being open. 11. Element according to any one or any of the claims 1-9, characterized in that at least one of said filler bodies (3) is compact, preferably consisting of foamed plastic material. 12. Element according to any one or any of the claims 1-9, characterized in that at least one of said filler bodies (3) consists of a shell of relatively dense material with filling of less dense material, preferably foamed plastic material. 13. Filler body (3) for use in making an element according to any one or any of claims 1-12, characterized by a) a major side (12), b) a side-wall section (6) extending convergently from the periphery of said major side (12) to c) a top section (7) contiguous with said side-wall section (6). 14. Filler body according to claim 13, characterized in that said top section (7) is dome-shaped with a smooth transition from said side-wall section (6). 15. Filler body according to claim 13 or claim 14, characterized in that it comprises, preferably integrally formed, engagement means (14,15) for engaging said lower reinforcing mesh (1,2). 16. Filler body according to any one or any of the claims 13 - 15, characterized in that it comprises, prefe¬ rably integrally formed, engagement means (16,17) for enga¬ ging said upper reinforcing mesh (la,lb,2a,2b). 17. Filler body according to claim 16, characterized in that said engagement means are constituted by upwardly directed resilient clamping fingers (16). 18. Filler body according to claim 16, characterized in that said engagement means are constituted by upwardly and/or laterally directed resilient locking ribs (17). 19. Method of making a reinforced concrete structure, characterized by the use of an element according to any one or any of the claims 1-12 for reinforcing the structure.

Inventors: LASSEN JOERGEN, LASSEN, JOERGEN
Applicants: LASSEN JOERGEN, LASSEN, JOERGEN
Application year: 1994
Main classification: E04B5
IPC codes: E04B5